"It brought a dark cloud in this room when you heard the news" about Rondo, Pierce said after Boston beat the Miami Heat 100-98 Sunday.

When head coach Doc Rivers told his players after the game, the joy of ending their six-game skid stopped, even if they had just outlasted the team with the best record in the Eastern Conference, which came into Sunday with a four-game winning streak.

Now the Celtics must try to keep winning without their leader, who tore the anterior cruciate ligament in his right knee late in Friday night's 123-112 loss, also in double overtime, in Atlanta.

They won Sunday after Pierce's 22-foot jumper with 31 seconds left gave them a 99-98 lead.

"Obviously, the Rondo news is pretty tough. I knew it before the game," Rivers said. "I just didn't think it was any time to tell any of our guys."

Sunday's game was the first in Boston for Ray Allen since he left the Celtics after five seasons and signed as a free agent with Miami. He scored 21 points.

LeBron James had 34 points for the Heat.

"As much as I've been a rival with Boston over the years, I never want to see anyone go down," James said. "It's terrible, not only for their team but for the league."